I learned of Mithridates VI of Pontus from A. E. Housman’s poem.
How is his name properly pronounced?
mith-ree-DAY-tees ?
MITH-ree-dates?
The scansion seems to favor four syllables.
Well, that’s a Latin version of the name, so I’d go with a Latin pronunciation. Best I can remember from Latin classes a couple decades ago:
mith ree DAH tays
Technically, I think the I is an “eee” sound, but it gets shortened sometimes.
I heard it as MITH RUH DIE TEES in some old movie, FWIW. Or perhaps some History Channel show. Probably the latter, I hear the voice of Edward Hermann saying it in my head.
DOT-eez or DATE-eez?
The metre of the poem provides an answer: mith-RID-uh-TEES or mith-RID-ih-TEES. That’s neither the Latin nor Greek pronunciation, of course. It also eliminates mith-ree-DAY-tees or MITH-ree-dates. Personally, I’d put more stress on “RID”.
PS: the last line is deliberately one syllable short, adding a bit of emphasis:
mith-RID-uh-TEES (pause) HE died OLD.
I disagree. The last line follows the same meter of the one two before it:
THEM it WAS their POI-son HURT,
and that gives the final line without altering the stress on the name’s penult :
MITH-ri-DA-tes, HE died OLD.
The general formula for romanized pronunciations (i.e if converting Japanese or Indian to latin characters) would, I assume, work for roman words.
a rhymes with saw
i rhymes with bee
u rhymes with boo
e rhymes with say
o rhymes with low
Mee-three-daw-tayz
Interestingly, that method of gaining immunity, named after this king, can work with some poisions:
… though I would not try it with arsenic. 
Inconceivable!!
I liked this part:
Now, tattoos used to be associated with tough guys, but that takes the cake. It is one thing to have a tattoo of a flaming skull, quite another to have a tattoo made with snake venom. 
And I disagree back! (In a friendly fashion.) The poem is in one basic meter, iambic tetrameter: u / u / u / u/
Unstressed syllables can be dropped, but only once, and the way to find out where it’s been dropped is to filter out the full feet. Here are the other seven-syllable lines. In almost all of them, the dropped syllable is in the initial foot (here blue). This is following the conventional rules.
There, when kings will sit to feast,
From the many-venomed earth;
Sate the king when healths went round.
They poured strychnine in his cup
Them it was their poison hurt.
In one line, he’s used trochees in the first half-line (green), and the dropped the unstressed syllable in the initial foot following the caesura (blue). Also allowed.
First a little, thence to more,
In the final line, the dropped syllable is in that same position, in the initial foot of the half-line following the caesura.
Mithridates, he died old.
If your pronunciation were to go, you’d have
Mithridates, he died old.
Uh-oh. I think I’ve brought myself round to your point of view with my own argument. Now I don’t know what to think. It’s more likely that he’s reapeating a pattern he’s used above than introducing a new one. Crap: I think you’re right, MITH-ri-DAY-tees.
Hmm.
While appreciative of everyone’s efforts…
I can’t help noticing that we don’t really see what one might call an emerging consensus, here.
Well, if all you want is a consensus, go for a dictionary!
This site says “mith-ri-DAY-tees,” as does this one. I can’t find anything authoritative to support my original suggestion. rats.
Doo dah, doo dah.
I don’t quite know why … but well done.
Foster actually used the same meter in the stanzas – trochaic tetrameter with the final unstressed syllable dropped: “CAMP town LA-dies SING this SONG / CAMP town RACE track FIVE miles LONG” The “doo dahs” and the refrain of course don’t fit.
I can’t cite but I’ve heard “mith-RID-ah-tees” on ancient history documentaries narrated by an English scholar. My professors said Mithri-DAY-tees.
I’ve wondered how the difference in syllable emphasis and pronunciation stars in two countries with the same language. The British scholars I’ve heard pronounce the name of Alexander the Great’s enemy, the emperor Darius, as dah- RYE-us instead of DARE-ee-us which is the standard American pronunciation. (His real name was of course way different- Darayashavuwa or something like it.)
When a Latin name is brought over wholesale into English, the usual rule is to Anglicize the vowels and leave the stress where it was in Latin. The ‘a’ in Mithridates being long, its syllable is the one that is stressed: Mithri-DAY-tees. The first syllable picks up a secondary stress since that is natural in English speech.
Greek names imported into English pass first through Latin like a sort of linguistic Ellis Island and are assigned stress according to Latin rules. The name Euripides is accented on the second ‘i’ in Greek but receives stress on the first ‘i’ in Latin, wherefore the location of the stress in English. And I would guess it is names like Euripides which are responsible for the by-pronunciation Mith-RI-da-tes mentioned above?
Going by the rule I just mentioned of Anglicizing Latin vowels and keeping the stress where it was in Latin, the pronunciation ought to be dah-RYE-us, since the ‘i’ is long in the Latinization of his name. That is also how this American pronounces his name. I am quite sure that the DARE-ee-us pronunciation is from assimilation with the army of Roman names ending in -ius like Julius, Cornelius, Marius, etc. where the ‘i’ is short and thus unstressed. I’ll warrant that at least until a generation or two ago, most Americans who knew of Darius met him not in the classics in an academic setting, but rather in the Bible in private reading.